Researchers at the University of Central Florida (UCF) have developed an optical oscilloscope. The instrument converts light oscillations into electrical signals to measure the electric field of light.
Due to the high speed at which light oscillates, measuring its electric field has been a challenge. The most advanced techniques powering modern phone and internet communications can clock electric fields at up to gigahertz frequencies, covering the radio and microwave regions of the electromagnetic spectrum.
Michael Chini, associate professor of physics at the University of Central Florida, oversaw the development of the world’s first optical oscilloscope. Courtesy of the University of Central Florida.
However, lightwaves oscillate at much higher rates, allowing a higher density of information to be transmitted. However, the tools currently available only resolve an average signal associated with a “pulse” of light and not the peaks and valleys within the pulse. Measuring the peaks and valleys within a single pulse is important because it is in that space that information can be packed and delivered.
“Fiber optic communications have taken advantage of light to make things faster, but we are still functionally limited by the speed of the oscilloscope,” said Michael Chini, associate professor of physics at UCF. “Our optical oscilloscope may be able to increase that speed by a factor of about 10,000.”
Complete characterization of optical waveforms requires an optical oscilloscope capable of resolving the electric field oscillations with subfemtosecond resolution and with single-shot operation. The team showed that strong field nonlinear excitation of photocurrents in a silicon-based image sensor chip can provide the subcycle optical gate necessary to characterize carrier-envelope phase-stable optical waveforms in the mid-infrared.
By mapping the temporal delay between an intense excitation and weak perturbing pulse onto a transverse spatial coordinate of the image sensor, the team showed that the technique allowed single-shot measurement of few-cycle waveforms.
The researchers will continue to investigate the method to determine how far they can push its speed limits.
The work was supported primarily through a grant from the Air Force Office of Scientific Research.
The research was published in Nature Photonics (www.doi.org/10.1038/s41566-021-00924-6).